Video tape producers of pre-recorded tapes aimed at sale or rental to the consuming public are concerned that their tapes will be duplicated by these consumers. In their attempt to safeguard against unauthorized duplicating, many producers reduce the vertical sync pulse width of the composite video signal recorded on the tape.
Since video tape recorders designed for the home consumers use these vertical pulses for reference locking during recording, this process, (providing the vertical sync is weakened sufficiently) renders the copying of such tapes either difficult or impossible.
Unfortunately it also follows that these weaker vertical sync pulses, also adversely affect the television on which these tapes are viewed, by making the viewed picture "roll, jitter" and become generally unstable.
On many older televisions, a "vertical hold" control exists which the consumer can adjust to a setting which will allow locking on weaker vertical sync signals. Many consumers however, cannot make this adjustment because they cannot find the vertical hold control location on their television set (it is often hidden inside panels etc.) or often is accessed by a plastic shaft protruding from a potentionmeter on the back of the television set and they simply cannot find it, or the plastic is missing.
It is also not uncommon for the television receiver to be in such a state so that the vertical sync processing circuitry is already weak, but plays standard pictures satisfactorily, but cannot handle the weak signals at any setting of the vertical hold control.
Further on the majority of late model televisions, there is NO vertical hold control at all, and the consumer is totally disappointed by being unable to watch their pre-recorded tape selection at all, and must return their purchase or rental to the retail shop for a refund, causing disappointed and dissatisfied consumers and unhappy businessmen loosing revenue.
Obviously a device which can reinsert the full vertical sync strength to the composite video signal would be of benefit to both consumer and businessmen alike. Further since the tape producers do want this weakened vertical signal on their tapes, a low cost device to WEAKEN the vertical sync would be of benefit to tape producers as well.
Further, since the present invention describes a new and novel way of reinserting full strength vertical sync into base band video cables, a very economical means can now be disclosed to "high frequency correct" the video signal passing from the base band video input connection of the invention, to the video output connection of the invention, all without the use of "active" devices, by using only "passive" circuit elements such as only resistors and capacitors and inductors.
Economical means to "high frequency correct" both the base band video and the unmodulated audio signals playing back from pre-recorded video tapes for the consumer market would be of great benefit to these consumers. Field testing of many pre-recorded video tapes for sale or rent shows that the audio signal invariably contains too much amplitude (volume), and too much "base" component; the circuitry disclosed here will very simply correct both defects of the audio, and also disclosed is a very simple means to correct for two of the most frequent base band video difficiencies; lack of definition or "detail", and excessive "noise", or signal to noise ratio, (high frequency components contain the noise).
Further if only one home video tape recorder and a consumer type home television is employed, an R.F. modulator to convert base band video to R.F. frequency was previously required, as well as was an audio modulator for the sound portion of the desired program. These R.F. modulators alone cost more to manufacture or buy than does the entire reinserter described in the present invention.